using System;
using Org.BouncyCastle.Math;

namespace Org.BouncyCastle.Crypto
{
	/**
	 * interface for classes implementing the Digital Signature Algorithm
	 */
	public interface IDsa
	{
		string AlgorithmName { get; }

		/**
		 * initialise the signer for signature generation or signature
		 * verification.
		 *
		 * @param forSigning true if we are generating a signature, false
		 * otherwise.
		 * @param param key parameters for signature generation.
		 */
		void Init(bool forSigning, ICipherParameters parameters);

		/**
		 * sign the passed in message (usually the output of a hash function).
		 *
		 * @param message the message to be signed.
		 * @return two big integers representing the r and s values respectively.
		 */
		BigInteger[] GenerateSignature(byte[] message);

		/**
		 * verify the message message against the signature values r and s.
		 *
		 * @param message the message that was supposed to have been signed.
		 * @param r the r signature value.
		 * @param s the s signature value.
		 */
		bool VerifySignature(byte[] message, BigInteger  r, BigInteger s);
	}
}
